Programming Interface Information:
This information is NOT intended to be used as Programming Interfaces of z/VM. |
RCPTE
Control Block Contents
RCPTE DSECT
Cross Reference (Contains links to field and bit definitions)
RCPTE Prolog
NAME : HCPRCPTE DESCRIPTION: REFERENCE AND CHANGE PRESERVATION TABLE ENTRY DSECT : RCPTE FUNCTION : A REFERENCE AND CHANGE PRESERVATION TABLE ENTRY IS USED TO KEEP TRACK OF THE REFERENCE AND CHANGE BITS FOR A 4K PAGE OF VIRTUAL STORAGE. LOCATED BY : THERE ARE NO POINTERS TO RCP TABLE ENTRIES IN THE SYSTEM. THESE ENTRIES MAY RESIDE IN ONE OF THREE PLACES: 1) A RESIDENT RCP PAGE (MAPPED THROUGH THE HOST VIRTUAL ADDRESS SPACE), 2) THE RCP BACKUP AREA IN THE PGMBK, OR 3) THE PGSTES CORRESPONDING TO THE PAGES THE RCP DATA REPRESENTS. CREATED BY : IF THE STORAGE KEY ASSIST IS NOT BEING UTILIZED: HCPPTRCP - RCP PAGES ARE BUILT WHEN SIE PAGE FAULTS ON AN RCP PAGE. HCPRCIRS - MOVES RCP DATA FROM THE RCP PAGE TO THE RCP BACKUP AREA. IF THE STORAGE KEY ASSIST IS BEING UTILIZED: HCPBPBCU - CREATES A PGMBK AND THEREFORE PGSTES THAT WILL CONTAIN RCPTES. DELETED BY : HCPRPBPA - THE RCP AREA IS CLEARED WHEN THE VIRTUAL STORAGE IS RESET. AN RCP PAGE MAY BE STOLEN BUT THE ACTUAL RCP TABLE WILL EXIST UNTIL THE PGMBK IS RELEASED. WHEN AN RCP PAGE IS STOLEN, THE BYTES ARE BACKED UP IN THE CORRESPONDING PGMBKS BY HCPRCISA. COMMENTS : - RCP DATA CORRESPONDING TO SYSTEM VIRTUAL PAGES WILL ALWAYS RESIDE IN THE PGSTES. - IF THE STORAGE KEY ASSIST IS BEING UTILIZED: - THE ARCHITECTURE DEFINES THE PGSRCP FIELDS AS THE LOCATION OF THE RCP DATA. - ALL RCP DATA IS SUSCEPTIBLE TO CHANGE BY THE STORAGE KEY ASSIST IF THE RCP INTERLOCK BIT IS NOT SET (RCP INTERLOCK BIT SERIALIZES CP AGAINST THE STORAGE KEY ASSIST AND VICE VERSA). - IF THE STORAGE KEY ASSIST IS NOT BEING UTILIZED - THE RCP AREA FOR A GUEST MACHINE CONTAINS ONE PAGE IN HOST VIRTUAL STORAGE FOR EACH 16 MEG OF GUEST STORAGE, STARTING AT THE HOST VIRTUAL ADDRESS CONTAINED IN 'VMDRCP'. THE RCP PAGES ARE CONTAINED IN THE HOST ADDRESS SPACE USED TO DESCRIBE GUEST STORAGE, BUT THE RCP AREA IS NOT DIRECTLY ADDRESSABLE BY THE GUEST. - IF THE RCP AREA PAGE IS MARKED INVALID IN THE HOST PAGE TABLE, THE RCP BYTE APPEARS IN THE PAGE MANAGEMENT BLOCK (PGMBK) WHICH REPRESENTS THAT MEGABYTE OF GUEST STORAGE, STARTING AT PGMRCPTB. - ONLY THE RCP DATA RESIDING IN THE RCP PAGE IS SUSCEPTIBLE TO CHANGE BY THE SIE MICROCODE. IF THE RCP DATA RESIDES IN THE PGMBK, SIE WILL NOT BE ABLE TO CHANGE IT. - SHARED STORAGE RCP DATA IS ALWAYS KEPT IN THE RCP BACKUP AREA.
RCPTE Control Block Content
RCPTE DSECT
Hex Dec Type/Val Lng Label (dup) Comments ---- ---- --------- ---- -------------- -------- 0000 0 Structure RCPTE REFERENCE AND CHANGE PRESERVATION TABLE ENTRY THIS CONTROL BLOCK DEFINES AN RCP BYTE (REFERENCE AND CHANGE PRESERVATION). THE FIELD IS DEFINED BY PROCESSOR ARCHITECTURE. DO NOT MODIFY THIS FIELD EXCEPT TO INSTALL ARCHITECTURE CHANGES. 0000 0 Bitstring 1 RCPBYTE HARDWARE RCP BYTE FOR ONE 4K PAGE 1... .... RCPLOCK X'80' RCP LOCK HELD .1.. .... RCPHREF X'40' HOST BACKUP REFERENCE BIT ..1. .... RCPHCH X'20' HOST BACKUP CHANGE BIT .11. .... RCPHOST RCPHREF+RCPHCH MASK FOR HOST BITS .... .1.. RCPGREF X'04' GUEST BACKUP REFERENCE BIT .... ..1. RCPGCH X'02' GUEST BACKUP CHANGE BIT .... .11. RCPGUEST RCPGREF+RCPGCH MASK FOR GUEST BITS THE RCP (REFERENCE AND CHANGE PRESERVATION) AREA IS USED TO ALLOW THE HARDWARE REFERENCE AND CHANGE BITS FOR A SINGLE REAL PAGE TO RECORD REFERENCE AND CHANGE INFORMATION FOR USE BY BOTH THE GUEST AND BY THE HOST. WHENEVER THE HARDWARE EMULATES A GUEST SET STORAGE KEY (SSK) INSTRUCTION, THE OLD VALUE OF THE R/C BITS FROM THE REAL PAGE ARE OR'ED INTO THE HOST R/C BITS IN THE RCP AREA, THEN THE REAL R/C BITS ARE SET TO ZERO, AND THE NEW GUEST R/C BITS ARE PLACED IN THE RCP BYTE GUEST R/C BITS. WHEN THE HARDWARE EMULATES A GUEST RESET REFERENCE BIT (RRB) INSTRUCTION, THE CONDITION CODE IS DETERMINED FROM THE LOGICAL OR OF THE R/C BITS IN THE REAL PAGE WITH THE GUEST R/C BITS FROM THE RCP AREA BYTE FOR THAT PAGE. THE OLD VALUE OF THE REFERENCE BIT IN THE REAL PAGE IS OR'ED INTO THE HOST BACKUP REFERENCE BIT IN THE RCP AREA BYTE, AND THE REAL PAGE REFERENCE BIT PLUS THE GUEST BACKUP REFERENCE BIT IN THE RCP BYTE ARE SET TO ZERO. WHEN THE HARDWARE EMULATES A GUEST INSERT STORAGE KEY INSTRUCTION, THE GUEST IS GIVEN THE KEY FROM REAL STORAGE, PLUS THE R/C BITS FROM THE REAL PAGE OR'ED WITH THE GUEST BACKUP R/C BITS FROM THE RCP AREA BYTE FOR THAT PAGE. WHEN SOFTWARE MODIFIES THE R/C BITS IN REAL STORAGE WHICH REPRESENTS A GUEST PAGE, THE SOFTWARE WILL LOGICALLY OR THE R/C BITS FROM REAL STORAGE INTO THE GUEST BACKUP R/C BITS FOR THAT PAGE PRIOR TO MODIFYING THE REAL STORAGE R/C BITS. IN ORDER THAT ONLY ONE CPU IS ACCESSING A PARTICULAR RCP AREA BYTE AT A TIME (EITHER BY EMULATION HARDWARE OR BY SOFTWARE SIMULATION), A LOCK BIT IS DEFINED IN THE RCP AREA BYTE. PRIOR TO STARTING ANY OPERATION INVOLVING THE RCP AREA, A LOCK IS OBTAINED ON THE RCP AREA BYTE BY ATTEMPTING TO COMPARE-AND-SWAP THE LOCK BIT ON. IF THE HARDWARE EMULATION FACILITY IS UNABLE TO OBTAIN THE LOCK, THE INSTRUCTION WILL BE PRESENTED TO SOFTWARE AS AN INSTRUCTION INTERCEPTION. 0001 1 Bitstring 1 RCPNEXT (0) NEXT RCP BYTE (ONLY TO BE USED IF THE STORAGE KEY ASSIST IS NOT BEING UTILIZED)
RCPTE Storage Layout
*** RCPTE - REFERENCE AND CHANGE PRESERVATION TABLE ENTRY * * +------+ * 0 |:BYTE | * +------+ * *** RCPTE - REFERENCE AND CHANGE PRESERVATION TABLE ENTRY
RCPTE Cross Reference
Symbol Dspl Value -------------- ---- ----- RCPBYTE 0000 RCPGCH 0000 02 RCPGREF 0000 04 RCPGUEST 0000 06 RCPHCH 0000 20 RCPHOST 0000 60 RCPHREF 0000 40 RCPLOCK 0000 80 RCPNEXT 0001
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